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[en] The photomultipliers comprise multi-alkali or bi-alkali photocathodes (types Sb-K-Cs and Sb-Na-K) and box and venetian-blind multiplier systems. THe dynodes consist of either a AgMg alloy or an antimony-cesium emitter on a nickel backing. The system is described of photomultiplier designations set by Czechoslovak standards. The specifications are shown in table of Czechoslovak photomultipliers. (H.S.)
[en] Laboratorial investigations of three objectives Industar-52 were made. The difference in transparency of the objectives is small and illustrated by figure 2, giving the transmissivity of the photometric system as function of wavelength, with different objectives inserted. Within the errors of measurements lying below 1% the objectives do not show appreciable of light and do not depolarize falling on them plane-polarized light
[en] An R and D project was started to develop a gaseous detector of single UV photons, able to stably operate at high gain and high rate, and to provide good time resolution and insensitivity to magnetic field, as required by the next generation of Ring Imaging Cherenkov Counters. The detector is based on the use of a novel and robust electron multiplier, the THGEM, arranged in a multilayer architecture, where the first layer is coated with a photosensitive CsI film. A systematic study of the response of single layer THGEMs with various geometries and different conditions was performed and several small photon detector prototypes have been built, tested in laboratory and operated in test beam exercises during 2009 and 2010 at the CERN H4 beam line. Evidence for the efficient detection of Cherenkov photons has been obtained, with stable operation in the test beam environment; the typical gain was about 105 and the time resolution was better than 10 ns.
[en] Distributions of propagation time of one-photoelectron signal through the photomultiplier during illumination of separate PhEhU-49B photocathode points ( as well as in course of photocathode uniform illumination) by short light pulses are experimentally measured. The width of distribution of one-photoelectron signal propagation time through the photomultiplier at half height of distribution maximum during uniform photocathode illumination constitutes 19 ns and is defined by photocathode periferal regions
[en] Fluctuations of signal propagation time (jitter) for the FEU-36 and the FEU-37 (95 and 37 samples, respectively) are measured by recording spectrum of photomultiplier signal lag from eight emitting diode. Total jitter estimates for the FEU-36 are approximation to zero amplitude of a pulse, actuating LED. Possibility of obtaining better time resolutions increases with photocathode sensitivity growth. Selection of the FEU-36 ensures reproducible time resolution of position lifetime spectrometers at about 250-300 ps under routine experimental conditions
[en] Intense electron beams are key to a large number of scientific endeavors, including electron cooling of hadron beams, electron-positron colliders, secondary-particle beams such as photons and positrons, sub-picosecond ultrafast electron diffraction (UED), and new high gradient accelerators that use electron-driven plasmas. The last decade has seen a considerable interest in pursuit and realization of novel light sources such as Free Electron Lasers  and Energy Recovery Linacs  that promise to deliver unprecedented quality x-ray beams. Many applications for high-intensity electron beams have arisen in recent years in high-energy physics, nuclear physics and energy sciences, such as recent designs for an electron-hadron collider at CERN (LHeC) , and beam coolers for hadron beams at LHC and eRHIC [4,5]. Photoinjectors are used at the majority of high-brightness electron linacs today, due to their efficiency, timing structure flexibility and ability to produce high power, high brightness beams. The performance of light source machines is strongly related to the brightness of the electron beam used for generating the x-rays. The brightness of the electron beam itself is mainly limited by the physical processes by which electrons are generated. For laser based photoemission sources this limit is ultimately related to the properties of photocathodes . Most facilities are required to expend significant manpower and money to achieve a workable, albeit often non-ideal, compromise photocathode solution. If entirely fabricated in-house, the photocathode growth process itself is laborious and not always reproducible: it involves the human element while requiring close adherence to recipes and extremely strict control of deposition parameters. Lack of growth reliability and as a consequence, slow adoption of viable photoemitter types, can be partly attributed to the absence of any centralized facility or commercial entity to routinely provide high peak current capable, low emittance, visible-light sensitive photocathodes to the myriad of source systems in use and under development. Successful adoption of photocathodes requires strict adherence to proper fabrication, operation, and maintenance methodologies, necessitating specialized knowledge and skills. Key issues include the choice of photoemitter material, development of a more streamlined growth process to minimize human operator uncertainties, accommodation of varying photoemitter substrate materials and geometries, efficient transport and insertion mechanisms preserving the photo-yield, and properly conveyed photoemitter operational and maintenance methodologies. AES, in collaboration with Cornell University in a Phase I STTR, developed an on-demand industrialized growth and centralized delivery system for high-brightness photocathodes focused upon the alkali antimonide photoemitters. To the end user, future photoemitter sourcing will become as simple as other readily available consumables, rather than a research project requiring large investments in time and personnel.
[en] The UCLA rf photo-injector system has been commissioned. All of the sub-components such as the high power rf, pico-second laser, rf photo-injector cavity, diagnostics, and supporting hardware have been tested and are operational. The authors briefly discuss the performance of the various components since the details of each subsystem are very lengthy. The laser delivers a sub 4 ps pulse containing 0-300 μJ of energy per pulse. The photo-injector produces 0-3 nC per bunch with an rf induced emittance of 1.5 π(mm-mrad)
[en] Charge lifetime of strained superlattice Gallium Arsenide photocathodes in dc guns is limited by ion back bombardment. In this work, we propose and present simulation results for an offset anode scheme to increase charge lifetime in dc guns. In this scheme, the axial symmetry of the cathode-anode configuration is broken by offsetting the anode transversely, while keeping the laser spot on the electrostatic center. This eliminates the bombardment of high energy ions on the cathode and enables maximum usage of the available cathode area. Depending on the size of the available cathode area, this method can increase the charge lifetime by an order of magnitude compared to the current best alternative method. An anode assembly, capable of in-vacuum movement, is required for this method, which has been designed and fabricated at Brookhaven National Laboratory. Authors: